Electro-magnetic relay

ABSTRACT

A relay is constructed from two flat superimposed quadrilateral yokes, each having four legs, and two legs of one yoke are connected to two legs of the other yoke by permanent magnets as well as by soft magnetic coupler and spacer pieces. The other legs serve as pole shoes for a swivel armature in a coil inside of the space circumscribed by the superimposed yokes. Corner elements mount the yokes to each other, and spring contacts extend from these corner elements and overlap contact surfaces on actuation carriers extending laterally from the arms of the armature. Connections are made through the corner elements or otherwise, laterally between the two yokes. The yoke assembly is enclosed by a circumscribing frame and covered on top and bottom with a foil.

United States Patent 1191 Renting et al.

ELECTRO-MAGNETIC RELAY Inventors: Hans-Werner Renting; Klaus-Dieter 'Wahnschaffe, both of Peine; Hugo Eggers, Eltze, all of Germany ELMEG Elektro-Mechanik GmbH, Peine, Germany Filed: June 25, 1974 Appl. No.: 483,052

Assignee:

Foreign Application Priority Data June 30, 1973 Germany 2333484 Nov. 18, 1975 3,211,858 10/1965 Juptner ..335/80 3,634,793

l/1972 Sauer 335/78 Primary ExaminerI-Iarold Broome Attorney, Agent, or Firm-Ralf H. Siegemund f r I g [unumiimn [57] ABSTRACT A relay is constructed from two flat superimposed quadrilateral yokes, each having four legs, and two legs of one yoke are connected to two legs of the other yoke by permanent magnets as well as by soft magnetic coupler and spacer pieces. The other legs serve as pole shoes for a swivel armature in a coil inside of the space circumscribed by the superimposed yokes. Comer elements mount the yokes to each other, and spring contacts extend from these corner elements and overlap contact surfaces on actuation carriers extending laterally from the arms of the armature. Connections are made through the corner elements or otherwise, laterally between the two yokes. The yoke assembly is enclosed by a circumscribing frame and covered on top and bottom with a foil.

32 Claims, 2 Drawing Figures US. Patent Nov. 18,1975 Sheet1of2 3,921,107

U.S. Patent Nov. 18,1975 Sheet20f2 3,921,107

ELECTRO-MAGNETIC RELAY BACKGROUND OF THE INVENTION The invention relates to an electromagnetic relay having two quadrilateral, annuloid yokes between which are mounted permanent magnets, a bobbin or coil carrier with a relay coil occupying substantially the whole of the space between the annuloid openings in the yokes; the carrier encloses an armature pivotably mounted between the yokes and the movement of the armature is adapted to actuate contact springs.

Relays of this type are already known. When mounted on a horizontal plate the yokes consist of two yoke portions extending horizontally in one plane and two further yoke portions bent inwardly at right-angles to the armature which is pivoted so as to move horizontally, said last-mentioned yoke portions determining the respective end positions of the armature. With this type of construction the two yokes are held together by spacing pins mounted at the four corners, while a permanent magnet is located between the two facing horizontal portions of the two yokes. Stirrup members are fixed to a horizontal baseplate carrying the soldering lugs. The contact springs situated beneath the yokes are also mounted on this baseplate, and the springs are being actuated by an actuating bar appropriately mounted at each end of the pivoting armature guided in a slot.

These relays require a relatively large number of parts such as the spacing pins connecting the soldering lugs and the baseplate supporting the contact springs and the stirrup members connecting said baseplate with the yokes, said parts being not absolutely necessary in the light of the experience gained in the present invention and consequently increasing the cost of production of the relay. In such case, moreover, the yokes must be brought into the correct shape by a bending operating, since owing to the need to accommodate a sufficiently large permanent magnet, the horizontal yoke portions must be spaced apart to a greater extent than the yoke portions running at right-angles thereto, and against the ends of which the pivoting armature is adapted to abut. The bending of the yoke parts must be carried out with a very high degree of precision and is relatively expensive.

The assembly of such a relay is, moreover, not particularly simple, since, for example, the yokes must first be interconnected by means of the spacing means after which the permanent magnet and the retaining stirrups must be mounted thereon. The retaining stirrups must then be fastened to the baseplate, on which latter contact springs have previously to be mounted in separate operations. Only when this has been done can the coil carrier be inserted within the yokes and the holding-on magnet be slid laterally between the yokes and through the coil carrier.

The chief drawback of such relays is the fact that the carriers and the relay coils project laterally beyond the yokes and are left exposed by the yokes. For this reason alone the relay must be housed in a separate cover so as to afford protection both from mechanical damage and also from the ingress of dirt.

When handling relays without separate covers the risk of mechanical damage or maladjustment of parts essential to the functioning thereof readily arises, since these parts are relatively freely exposed and can easily be touched. During operation, however, a cover inhibits heat exchange with the ambient atmosphere, which is detrimental for relays having a high switching and/or excitation capacity.

DESCRIPTION OF THE INVENTION It is an object of the present invention to avoid the afore-mentioned drawbacks and deficiencies and to provide for a compact relay construction, which requires only a few, simple parts, many of them having similar contours, and which can be assembled rather easily, e.g. by an automated assembly process. The relay is to be of stabil construction, even without encapsulation, and must be magnetically screened, flat and fit, e. g. on p.c. cards to be placed in racks. Encapsulation, when needed, should be possible but withou separate cover.

In accordance with the preferred embodiment of the invention, it is suggested to provide two yokes of quadrilateral construction, each having a central, quadrilateral opening, so that each yoke has four legs facing each other in pairs across that opening. The two yokes are superimposed and mounted in spaced-apart relation with alignment of the openings and of the legs, whereby permanent magnet means and magnetically conductive inserts or spacers provide for magnetic interconnection of the yokes and define their distance. Coil, coil carrier and armature are mounted in-between and occupy not more space than defined by the spacedapart distance of the respective planar outer yoke surfaces. Hence, the outer dimensions and boundaries of the assembled yokes constitute the outer dimensions of the relay as a whole.

As a consequence, the yokes as assembled constitute a rather sturdy frame and provide also mechanical shielding of the contacts and contact arrangements which are disposed inside of the two-yoke assembly. The permanent magnetic and flux coupler elements function as spacers for determining the distance between the yokes as accurately as machining of these spacer parts permits. That in turn defines the operative air gaps as between yokes and armature rather accurately. v

The yokes are preferably mounted to each other by corner mounting assemblies, made of electrically insulating material and-the leads to the interior run through these corner assemblies. Contact springs extend from the corner assemblies for cooperation with contacts mounted on the relay armature, particularly the ends of the arms of that armature. This way, one does not need a separate mounting assembly for the contacts; the yoke mounting corner elements (e.g. four of them) provide for the needed support, while ultimately the contacts bear (indirectly) against the yokes as assembled.

The contact springs extend from the comer mounts of the yokes, towards contact carriers on the armature which carriers extend laterally from the arm ends of that armature. This way, armature displacement is directly translated into contact action, whereby the contact pressure is provided by the resiliency of the springs as extending from the corner mounts.

The armature may extend with its arms in-between the spaces as defined by and between respective two legs of the two superimposed spaced apart yokes, and the contact carriers as well as the springs as extending from the corner mounts extend into that space. Thus,

the yokes themselves provide protection of the contacts against interference.

The contact carriers on the armature are preferably relatively rigid, and therefore, will have the same speed as the respective armature end which enhances contact breaking speed and avoids oscillations of and in the movable armature system. On the other hand, the provision of flat contact carriers in the space between two legs respective of the two yokes establishes air cushioning for the arm of the armature, breaking impact on a stop sheet right on the yoke.

The two lateral, flat contact carriers on each armature arm give these ends wing-like appearance and transverse motion is, indeed, cushioned. If the contact springs are made also flat, they do likewise displace air on deflection, which has also a certain cushioning effect. In the case of relay action, the resulting movement of displaced air along the carrier provides also for contact cooling as well as blowing of any sparks. The movement of these sparks is further quickened by providing for amagnetic field along the carriers.

The contact springs are perferably impeded as to reverse resilient deflection in direction of contact opening. Thus, when contacts are (accidentally) welded together, further armature movement is blocked and the armature with its contacts will not be able to assume the opposite switching state. This, however, presupposes that the armature is positively journalled.

Since the yokes are of flat design, no other auxiliary spacer members are required. The exact spacing between the yokes is determined by the magnets, the surfaces of which are in any case flat ground, and which, therefore, also act as gauge blocks, also achieving exact spacing between the yokes in the armature stop regions and accordingly ensuring that the air gaps are accurately dimensioned. As there are no projections beyond the yokes, the relay can be of very flat or squat design, so that it can be accommodated on card within the customary card spacing.

The relay according to the invention offers a further particular advantage in that it can be manufactured as a sandwich construction especially by largely automated fabrication methods. In this connection, all func- "tional'parts of the relay can be placed upon one flat yoke whereupon the second yoke is superimposed and suitably secured to the first yoke. The contact springs and their leads and the entire actuating mechanism are accommodated in the cavities or recesses necessarily 'formed between the wide yokes covering all parts. This factor, together with the suitable design of the soft iron filler pieces of the magnetic system, results in a relay of both very small physical dimensions and high switching and low excitation capacity or if compromises are made in respect of the physical dimensions, to an ample dimensioning of the magnetic path, so that magnetic leakages which are detrimental to adjacent components and also to the functioning of the relay are avoided as far as possible.

As the contact springs are mounted in the region between adjacent corners of the yokes and extend towards the ends of the pivotable armature, the assembly technique for the contact springs in conjunction with the corner assemblies simplifies the sandwich construction, while at the same time requiring only a minimal space and permitting a simple design 'of contact spring to be used. In order to hold the yokes together and to clamp the springs between the spacers, rivetspassing through the yokes and the spacers may, for example, be used, so that all together only four connections are required at the edges of the yokes to hold the complete relay together. The feature of supporting the contact springs against the yokes by means of the spacers also renders unnecessary the use of a separate baseplate for mounting the contact springs.

In order in such case to secure the springs and the spacers against lateral twisting or displacement, all three members, the spacers, the yokes and the contact springs, inter-engage by means of notches or recesses. For this purpose, it is of advantage for at least one of the spacers of each corner assembly to be provided with an extension which insulates electrically at least one of the yokes on one side. It is possible in this manner with simple means to make all the external electrical connections to the relay without having to increase the dimension of the relay the feature of distributing these connections around the periphery thus providing maximum spacing between the electrical connections to the relay, which is extremely advantageous, especially for sub-miniature relays.

A further advantageous feature of the invention resides in the fact that contact carrier and actuating members of insulating material are mounted laterally on the ends of the pivoted armature, which extend into the region of the contact springs mounted adjacent the yoke corners. As these contact actuating members carry contacts and are likewise overhung above and below by the yokes, they are thus protected against accidental handling and maladjustment. They can nevertheless be easily attached to the ends of the armature by virtue of the sandwich assembly technique.

These contact actuators may likewise actuate noncaptive spring contacts mounted between the spacer members; a special advantage is, however, achieved if the contact carriers and actuators are provided with contact surfaces which co-operate with the contact surfaces of the contact springs mounted in the region of the corners of the yokes. In this way, not only is the use of separate non-captive springs avoided, but less space is alsoneeded, since, as a rule, additional space must be made available to accommodate relatively long and flexible non-captive springs.

Moreover, the feature of providing contact surfaces on the contact carriers and actuators ensures a more positive and reliable switching operation, since the movement of the armature causes the switch contacts to operate directly without the interposition of coacting transfer members. This feature also causes the contacts to separate with the maximum speed, since the contact surfaces on the contact actuators move with the same acceleration as the pivotal armature. This has a positive effect in 'tne event of any burning of the contacts, since owing to the high speed of separation of the respective contact surfaces, it is not so easy for powerful and prolonged arcing to build up.

The arrangement of the contact surfaces as outlined above reduces very considerably any tendency by the contact to bounce, particularly, because the contact surfaces are rigidly connected to the mass of the armature, i.e. without the interposition of any resilient member. Therefore, the contact carriers even in cooperation with the magnetic forces as acting on the armature, do not constitute an efficient oscillatory system.

The mounting of the Contact surfaces'on the contact actuators also enables the providing of magnetic blowing for causing any spark that may develop to wander over the contact surfaces and not to stay at any definite point. By this means, spark erosion of the contact surfaces is considerably reduced and the useful life of the relay is prolonged. Spark quenching is further enhanced by the fact that wide contact surfaces are moved transversely to their extension, thereby causing conciderable amounts of air to be displaced resulting in air blowing against the spark and providing additionally air cushioning as already mentioned above.

The employment of annuloid yokes and the mounting of contact actuating members, where appropriate on both sides of the ends of the pivotal armature and the corresponding mounting of contact springs between the corners of the yokes, results in a completely symmetrical structure of the whole relay, so that in many applications, although normally the pivotal armature is mounted so as to be tiltable about a fixed axis, the possibility arises of inserting the pivotal armature into the bobbin or coil carrier without its axis of rotation being on a fixed mount. This is problematical, because there is static redundancy in this case. By this means, the use of any necessary expensive devices for the mounting of the axle of a pivotal armature are avoided. The movement of the pivotal armature is controlled by the symmetrical distribution of mass and the symmetrical effect of the magnetic and spring forces, without causing it to cant or to be displaced from within the bobbin.

With safety relays, however, i.e. relays where reliability of signal sequence-controlled contact making, must be obtained, a bearing mounting for the axle of the armature is indispensable. In such a case, it is, in fact, necessary that the armature should not be displaced under the influence of any external excitation or not be displaced to such an extent that it closes contacts which it would normally be caused to close, if one of the previously closed contacts had welded owing to overloadmg.

A further feature of the invention resides in the fact that substantially all the electrical connections for the contacts and the relay-coil are led between the two yokes out to the lateral wall or walls of the relay. This is easily possible, since the yokes lie parallel to one another and the contact springs are mounted at the corners in or between the spacer pieces. By this metlnd of bringing out the electrical connections, the maximum possible spacing between them is achieved, which is of particular importance for subminiature relays. The ends of the contact springs remote from the pivoting armature may readily be used to make soldered or plug-in connections at the side of the relay by being ,bent downwardly or they can form direct electrical contacts on the side of the relay for the electrical connections thereto.

Yet another very advantageous feature of the invention consists in connecting at least one of the spacer members at each corner to a one-piece or composite casing surrounding the sides of the yokes. A simple cover for the sides of the relay is thus produced which is adapted to produce a dust-tight seal or even a hermetic seal depending on the type of relay. The casing for this purpose, may, for example, be made by injection molding technique in one piece together with the spacer members. In a preferred method the middle spacer member is connected to the casing. The other spacer members may, however, also be injectionmolded in one piece with the casing, by connecting them, for example, to the middle spacer member by means of thin web pieces, which when drawn together can be deformed so as to grip the contact springs firmly. In the course of the sandwich-type assembly of the relay, the casing is simply assembled together with the spacer members. Foil covers on top and bottom offer a simple means of protection without requiring any head space above the yoke and frame assembly.

This casing also affords a further advantage. In order especially with sub-miniature relays having numerous contact and coil connections to be able to bring all of them to the outside of the relay, which is essential with a printed circuit system, or in order when dealing with fewer connections to be able to select where they are to be brought out and thus simplify the assembly, the casing may be provided with vertical grooves, the bottoms of which are alternately offset in depth by half the thickness of a module, the electrical connections being then located in said groove bottoms. The connections are thus in projecting and recessed relationship to one another. By this means, approximately twice as many connecting sites can be arranged on the periphery of the relay than would be possible without the provision of the grooves in the casing.

When bringing the connections out at the side of the relay, it is easily possible according to a further feature of the invention with or without the casing to provide a frame-like plug connector open at top and bottom and having a depth not greater than that of the yokes on the assembled relay, on the inner side of which springs are provided corresponding positionally to the external connections of the relay and connected to soldering tags projecting downwardly beyond the plug frame. Plug connections for relays are often desirable, but in general they require too much additional headroom, so that it is then no longer possible to fit the relay into a printed circuit. This is possible, however, with the design according to the invention. The plug connector has in fact no bottom, so that the relay snaps into position when plugged into the printed circuit plate, on which the plug connector is soldered or otherwise fastened. The sandwich assembly technique of the relay described herein thus enables a plug-in model to be developed which even in the assembled condition requires no greater headroom than that required by the relay itself by virtue of the spacing of the outer comers of the two yokes. The plug connector has at the outside the same height but its height is usually even less than this spacing.

In the relay the contact springs are relatively short and wide and owing to the fact that they are clamped between the spacer members they take up a comparatively accurately fixed position even outside the clamping zone, and it is rather unlikely that they will be bent during preparation and assembly owing to their short length and the comparatively large clamping area. As the contact domes on the contact springs are preferably made by a punch in the prescribed shape after welding on, they are automatically always at a uniform contact height in relation to the back of the spring. In such a relay the position of the contacts is consequently accurately fixed without incurring any special expense, so that subsequent adjustment is as a rule unnecessary.

In cases where adjustment nevertheless becomes necessary, a simple adjusting procedure is available for this purpose owing to the construction of the relay according to the invention by virtue of the flat yokes facing and covering the contact springs at all points. This procedure consists in temporarily adjusting the position of the pivotal armature by means of a feeler gauge so that the contact on the armature touches its countercontact, whereupon an oblong cross-sectional rod is inserted between the spring of the counter-contact and DESCRIPTION OF THE DRAWINGS While the specification concludes with claims particularly pointing out and distinctly claiming the subject matter which is regarded as the invention, it is believed that the invention, the objects and features of the invention and further objects, features and advantages thereof will be better understood from the following description taken in connection with the accompanying drawings in which:

FIG. 1 is a perspective view of a relay in accordance with the preferred embodiment of the invention showing partially broken open portions to permit viewing of the interior; and

FIG. 2 is a perspective view of a frame and housing part.

' Proceeding now to the detailed description of the drawings, the relay illustrated has two quadrilateral yokes l and 2, which could be regarded as rings or annuloids of rectangular contour, each yoke having four legs accordingly. A permanent magnet 3 and an intermediate piece 4 is disposed between two adjacent legs of yokes l and 2, there being a corresponding assembly interposed between the two oppositely located legs of the two yokes. These intermediate pieces 4 function as spacers and are quite accurately machined. The same is true for the magnets 3, so that the distance between the two yokes 1 and2 is accurately determined therewith. v

A bobbin or coil carrier 6 is disposed in the open space in and as between the central portions of yokes 1 and 2; this carrier 6 carries an energizing coil 5, while a pivoting armature 7 is disposed inside of bobbin 6. Armature 7 has a shaft or axle 8 for journalling the armature in plastic aperture disks 9. These disks are mounted in carrier 6. The armature 7 can pivot in one orthe opposite direction and its extremeties or arm ends can engage diagonally opposed yoke legs, serving as pole-shoes accordingly.

As all parts are circumscribed by the yokes, they can generally be made relatively wide especially in the region of the permanent magnets, so that the thickness of the latter which must be of a definite volumetric capacity, can be kept relatively small. This offers a number of significant advantages; among them is that these permanent magnets may have a relatively low magnetic internal resistance, which is important from the point of view of increasing the sensitivity of the relay. Since the permanent magnets are actually situated in the magnetic circuit of the excitation flux, that flux would have to be made greater in proportion to any increase in the magnetic resistance in the magnetic circuit.

The gap between the two yokes needs only be partly filled by the flat permanent magnet 3, the remainder being occupied by soft iron parts 4. In such a case, the thickness of the permanent magnets and that of the soft iron parts determines the spacing between the yokes l and 2. In view of the ample space made available by the use of wide yokes, the soft iron parts may in this case be designed so as to form a magnetic shunt; by this means the smallest possible magnet volume and the lowest possible internal resistance of the permanent magnet system situated between the yokes may be arrived at for a given relay by suitable optimization.

The two ends of armature 7 each carry two laterally extending contact actuators l0 and 11, made e.g. of plastic material. These actuators are secured to the respective armature arm by means of a magnetizable rod or bar 13, which is inserted in a slot 12 at the particular armature end. Each of the actuators l0 and 11 has a Contact surface 14 on its respective upper or top side, and another contact surface 15 on its lower side. Hence, these contact surfaces are moved up and down on pivot motion by the armature 7 and constitute noncaptive contacts. The entire arrangement has eight such contact surfaces, the sub-assembly as illustrated in the front of the perspective illustrationis dublicated in the rear. 1

Each contact surface on the rocking or pivoting armature cooperates with a stationary contact 16 having curved, cylindrical contour as facing the respective armature contact. Contacts 16 are stationary in the sense that they are not mounted on the armature, but they are displaceable due to mounting on leaf springs, such as 17. A leaf spring 18 is shown partially, carrying also a contact, such as 16, which cooperates with a contact surface 14 on an upswing of the armature.

Due to the swivel, pivot or rocking motion and dis placement of the armature, one arm of the armature will deflect two springs 18, with a reversal of deflection action on pivoting to the respective other position. The illustrated position of the armature shows the end which is visible in the front due to perspective illustration,in up position, so thatfcontact carriers 10, 1 1 defleet the two visible springs 18. The rear end of thearmature is down accordingly and has deflected the two springs corresponding to 17. Each armature end does not abut a yoke leg directly, but sits on a stop sheet 33.

The relay has four comer assemblies, one assembly being shown in greater detail and being comprised of spacer pieces 19, 20 and 21, These leaf springs 17 and 18 are secured to these spacer assemblies. These assemblies actually serve as mounting structures in that rivets, such as 22, hold spacer assemblies and yokes together in the four comers. The springs are mounted with the assembly in that fashion and the rivets force super-imposed parts together. Not all of the spacers 19,

20, 21, springs l7, l8 and yokes 1 and 2 have all of the illustrated recesses and protrusions in all four corners. One protrusion or extension is, for example, flange part 23 being inserted in an appropriate recess in the one corner of yoke 1 and providing also electrical insulation relative thereto. Rear end continuations 24 of the contact springs may be run down at that point. The spacer 21 may, be provided with a similar flange inserted in a recess in yoke 2, but that may not be necessary.

The contact springs 17 and 18 have similar contour each with a laterally offset rear extension 24 and since the contacts 16 of two springs 17, 118 face each other, the narrower extensions 24 have necessarily a lateral distance from each other. Since in this manner the width of such a contact spring extension 24 is invariably only a small fraction of the width of the springs themselves, in the case of facing contact surfaces of two springs, the extensions thereof are always spaced from one another, which ensures trouble-free electrical connection. If in this connection two contact springs l7, 18 with facing contacts 16 are provided at each corner of the relay, all springs mounted at the corners have coincident contours, so that only a small number of different components are required, which brings further advantage to the sandwich method-of construction. Should more than two contact springs with facing contact surfaces be required at the corners, the extensions or leads can be mounted at right-angles to the longitudinal edges of the contact springs,'so that they can then be led out by another lateral surface of the relay.

The rivetting of the yokes to each other provides also for positive positioning of carrier 6 inside of the structure. The carrier has projections, such as projection 34 of the coil flange bearing against the yokes l and 2. The particular projection 34 is also provided with an electric connection 35 for coil runs to the outside of the assembly.

Each contact surface 14 and is connected to an elongated supple spring, such as 25, running parallel to the armature and providing current to the respective contact surfaces. The spring doubles back and is run to the outside through the respective, associated corner piece 20.

Each actuator 10 and 11 has additionally two permanent magnetics 26 and 27 providing one magnetic flux component in direction of the respective contact surfaces 14 and 15. These particular flux components establish a force acting on an arc or spark between a contact surface on the one hand and its respective counter contact 16 on the other hand and in direction of longitudinal extension of that counter contact so as to drive the spark in axial direction as far as the cylindrical contour of the contact 16 is concerned. Therefore, such an arc will not remain stationary at the point of development and will not burn a hole. Rather the arc will migrate along the contact surfaces and will not unduly heat anyone spot. Damage is avoided or at least minimized by such a provision.

In lieu of the two small permanent magnet rods 26, 27, one can construct rod 13 as permanent magnet. Still alternatively, if the rod 13 is made of soft magnetic material, stray and leakage flux can be put to use and is appropriately run into such rod to obtain the same effect of moving an are over the contact surfaces.

Owing to the relatively large cross-section of the yokes and of the armature made possible by the construction and technique of the invention, permanent magnets do not produce any detrimental effects on the contact actuating members in respect of a too rapid saturation of the flux path provided for the adhesion of the pivotal armature and for the actuation thereof.

The ends of contact springs 17 and 18 as well as of springs 25 are all constructed to lead to connections 28 in and at the respective closest comer element 20. These connections 28 may be connected to or engage springs 29 of a plug connector 30. The connector 30 is constructed as a frame into which the entire relay yoke structure has been inserted. The springs 29 are equipped with soldering pins or lugs 31, which can be soldered onto a printed circuit board.

The plug connector 30 is constructed as a frame and has adequate dimensions for receiving the yokes as riveted together. The height or depth of that frame should not exceed the heihgt of the yoke assembly. This way, no additional head room has to be provided for, the frame 30 as circumscribing the yoke assembly encases the yoke assembly and the top and bottom opening of the yoke structure may be covered by a thin foil. The yoke assembly may be just stuck into the frame, and two of its sides cover the laterally open space between those yoke legs which serve as pole shoes. Two opposite sides of frame 30 have recesses 32, so that the yokes as assembled can be gripped by at least one yoke, so that the yoke assembly can be removed from the frame.

The legs of the yoke themselves cover all contactmaking parts of the relay and are relatively wide. This wide construction does not only serve as protection, but the permanent magnets 3 may also have very large base surfaces and offer, therefore, very small internal resistance (reluctance). As stated, the magnetizable spacers 4 provide for a magnetic shunt path which reduces the magnetic resistance regarding energizing flux still further, while the volume of magnetized material is quite small. The sensitivity of the relay benefits greatly from this feature.

Another advantage of the wide yoke legs is that the rocking or swivel armature can be correspondingly wide. The operating air gap between armature and yoke legs has, therefore, quite a wide surface, and magnets of small height can be used which in turn renders the relay quite powerful, particularly with regard to contact pressure forces.

The wide armature and the wide actuators displace a relatively large amount of air when actuated. The armature is caused to pivot from one end position to the other one. If the relay construction is laterally closed that air must flow from one armature arm along the space between the contacts to the other arm. This flow dilutes the ionized plasma of a spark or arc and provides also for cooling of the contact surfaces along which such air is forced to flow. Still, residual air between the large surfaces, which are moved towards each other, cushion the impact of the respective armature end on the yoke. The separation or stop sheet 33, moreover, prevents direct impact on the yoke. This cushioning extends the life of the relay and of its contacts, and prevents bouncing of the armature as carrying contacts, so that contact bouncing on account of armature-yoke impact is impeded, indeed.

The wide construction of the yoke legs permits also utilization of wide springs 17 and 18. Hence, a relatively large quantity of air is present between each spring and the nearest yoke leg. This air dampens any displacement of the contact springs l7, l8 and that in turn impedes bouncing of the respective relay contacts. Besides, the springs are quite short and have accordingly a high spring resilient spring constant while contact pieces (16) plus spring have comparatively small mass. The relevant factors of such an oscillating assembly are, therefore, mutually reinforcing as to damping and are quite poor in performance for setting up of oscillations. The air cushion imposes additionally 3,92l,lO7

strong attenuation of mechanical oscillations, so that. indeed, there will be little, if any flutter and bouncing.

The contact surfaces 14 and 15 are secured to the armature in a manner which does not permit oscillations relative to the armature. The springs 25 are to have little resiliency. Thus, the armature plus contact actuators constitute an oscillation system, which is characterized by large mass and large magnetic forces. The effective inertia of the armature is so-large, so that in the instant of impact of the contacts (14 or 15) on contacts 16, armature 7 continues its displacement, practically unimpeded. The large armature mass preeludes all bouncing at this point. As the armature hits the yoke, i.e. stop sheet 33, maximum magnetic force exists in the circuit. These attracting forces hold the armature against reflective bouncing. Moreover, the air cushion did reduce the kinetic force of the armature right before the impact. Even a slight bouncing of the armature will not be effective and will be compensated by the resiliency of the mount of contacts 16, only the deflectionof springs 17 and 18 may vary slightly but without causing the contacts to disengage and reopen.

It should be noted that one can increase the attenuation of springs 17, 18 still further by providing the corner elements 19 and 21 with inward projections to confine the air adjacent springs 17, 18 still further, so that more tortuous paths for air between springs and yokes are provided therewith, and cushioning is enhanced accordingly.

Still further increase of contact spring damping is possible by placing e.g. a foam material between springs and yoke, filling that space and cushioning any spring deflection still further.

The corner pieces are constructed to prevent springs 17 and 18 from following the contact surfaces 14 or 15 upon opening action of the relay contacts. For this, ridges 36, 37 are provided on an inward extension of corner piece 20. These ridges shorten the spring arm length to such an extent that they hold the spring with contact 16 in position particularly upon opening contact action. These stops do not interfere with desired flexing of each contact on a spring 17 or 18 once engaged, and as the armature continues to move until hitting a pole shoe-stop sheet, the flexing of the springs 17, 18 produces the desired contact pressure.

An advantageous feature of the uni-directional resiliency as imparted by the stops 36, 37 upon the contacts 16 on springs 17, 18 is that upon abutment, they will open rapidly without tendency to reclose once disengagement has been effected, as the stops impede further movement of contacts 16. On the other hand, the contacts may be welded together. As the armature pivots to switch over, the springs welded to one or more of the corresponding contact surfaces provided on the contact actuating members 10, 11 can only be carried by said contact surfaces as far as the stops on the middle spacer piece will permit. At this moment any further armature movement is blocked, if the axle thereof is mounted with sufficient play. Accordingly, the oppositely facing contact surfaces on the contact actuator, not being welded. cannot touch their counter-contacts 16 and thus no previously open contacts can be closed.

It can thus be seen that contact-making occurs within two ranges between the contacts on carriers 10, 11 on the one hand, and the contacts 16 on resilient spring contacts l7, 18 on the other hand. As repeatedly stated, the illustrated position of the armature shows the visible arm end in up position with engagement between contact surfaces 14 and contacts 16 on upwardly bent springs 18. The resilient reaction of these springs provides for the requisite contact pressure.

On energization of the coil 5 for causing the armature to change position, the visible front end will begin to recede from the abutment position with the one leg of yoke 2, and tension of the springs 18 will relax, until they abut ridge 36 which prevents them from any further displacement and the contacts will open. The armature will continue to pivot until contact surfaces 15 abut the contacts on springs 17 which are being bent and will provide for the requisite contact pressure particularly after this arm end of the armature 7 has impacted on the visible stop sheet 33. The contact carriers 10, 1 1 do not contribute to the contact pressure and are hardly deflected at all.

The contact springs may have to be adjusted or, more precisely, one may wish to adjust the length of the travel path of the contact carrier as between the spring loaded counter contacts. One can, for example, place feeler and adjustment gauges between yoke 2 and e.g. the upper side of armature 7 so that the latters position is adjusted to obtain the desired contact making as between a contact surface 15 and the respective countercontact 16 on a spring 17. Now a rod with oval crosssection is placed between the latter spring and yoke 1 and turned until actual contact making between the contact 16 on that spring 17 and the contact 15 is obtained. The instant of contact making can be indicated electrically by utilizing the contact making action in an indication circuit connected to the relay for purposes of this adjustment. The spring is then bent appropriately. Resilient retraction of the spring as resulting from retraction of the oval rod can be taken into consideration by chosing a slightly thinner feeler gauge as would be needed otherwise.

As a further development of the adjustment procedure according to the invention, it is also possible to turn the rod by means of an electric motor and to switch off the motor when contact is made between the movable contacts and the counter-contacts. By this means, automatic adjustment becomes possible, which effects a considerable saving in time otherwise required for adjusting the contact springs with conventional relays. In order to effect a still greater saving in time, provision can be made for the location of individually operated rods between the contact spring concerned and the adjacent yoke when dealing with a plurality of contact-springs mounted at the yoke corners. During a still more completely automated procedure, a plurality of contact springs may be reliably adjusted simultaneously in this way.

In general, however, it is possible to dispense entirely with the need for adjustment with this type of construction. As already described, the sandwich construction affords the possibility of keeping within important reference dimensions with very considerable accuracy and with simple means. it is, therefore, highly unlikely that the need would arise for adjustment of any contact actuating members secured inaccurately on the armature. These members are, in fact, fixed to both sides of the armature ends with a flexible material and can thus be bent into shape by means of a suitable appliance during the manufacturing process, so that the contact surfaces of the actuating member accurately take up the prescribed position at least at the point of contact making as between a contact on the carrier and the respective spring-loaded counter-contact.

The armature 7 is shown as being joumalled by means of shaft 8. However, the relay is constructed completely symmetrically in relation to the turning and pivot axis of armature 7 and all movable masses and magnetic forces are likewise symmetrically, distributed. Hence, such joumalling of the armature can be dispensed with, provided one does not need absolute certainty with regard to any contact making signal sequencing. The armature 7 will nevertheless retain its prescribed disposition inside of the carrier 6. Moreover, springs 25 provide some additional guiding for the armature.

As one can see from the drawings, springs 25 are constructed to have rather small spring constant, one utilizes here the torsion of the double-backing configuration. This small spring constant can be established in that manner. even if the wire itself is rather thick. A rather thick, i.e. large cross-section for the wire of springs 25 is needed so as to run sufficiently high current to the contacts. Moreover, these springs 25 should not interfere with the generation of large contact pressure forces. The ends of springs 25 are one of the connections 28 at each corner, or they could be brought out to the outside on the closest side, as between facing yoke legs, held spaced apart by the corner assemblies.

The relay as shown is rather easily encapsulated. The two aligned central openings in the two yokes can be covered by foils made of metal or plastic. Particularly, metal foil can be hermetically sealed to the yoke by welding, by sticking, bonding, welding or otherwise.

FIG. 2 shows an outer jacket or casing 38 for the relay. This casing is fabricated to incorporate comer pieces as well as the stops 36 and 37 on the extension. in this connection, the spacers l9 and 21 are also molded together with the spacer piece 20, and are connected with the latter by thin lateral webs. During the assembly of the relay this casing 38 with the spacer pieces is included in the components and thus encloses the relay laterally, so that the gap between the yokes 1 and 2 is covered at the sides. The relay is thus encapsulated at least in a dust-tight manner at the sides. The casing 38 may be made up of several parts, for example, of two of the parts as shown in FIG. 2, each being of single piece configuration or the casing is a whole may also be fabricated as a single piece.

Slots 41 are provided in the casing 38 for purpose of receiving the connections 28, and/or the extensions 24 of the contact springs and other corresponding leads from the relay coil connections. If the relayis to be hermetically sealed, these slots can easily be sealed subsefastened to the yokes through the connecting together of these yokes, because the rivets 22 or the like, holding the yokes together traverse also corner pieces 20,

' the contact springs as passing through the slots in the casing are indirectly also secured in their correct position.

The periphery of the casing 38 is provided with grooves 39 and 40, the bottoms of which are staggered in relation to one another by half the thickness of a module and which accommodate the electrical connections 28 for the contact springs and the relay coil. It is thus possible to accommodate a large number of connections for contact springs and relay coils on the periphery of the relay, without encountering the difficulty.

'quently. It is clear moreover that this casing is readily of providing adequate insulation. These connections may consist of downwardly bent soldering tags or of other simple connections. If a plug connector 30 is placed around the casing 38, the springs 29 of the plug connector 30 will engage the contact lugs or the like as projecting through slots 41. In the latter case, obv'misly the springs 29 must be designed so that they are able to make contact with the bottoms of the grooves 39 and 40.

The relay can be constructed rather easily and is particularly suited for automated manufacturing, because it has a sandwich construction. One begins the assembly by mounting the several parts onto yoke l and places the second yoke on top and rivets them together. The several contact springs and leads and the armature etc. are all placed more or less inherently in the spaces, places and cavities as provided for that purpose. The

width of the yoke legs facilitates greatly design of these mounting spaces for ease of manufacturing. This sandwich construction and here particularly the desing of the magnetic path from one yoke to the other permits compact construction for a high ratio of switched power to energizing power. Moreover, the design provides very little magnetic stray effects outside of the relay.

The invention is not limited to the embodiments described above, but all changes and modifications thereof not constituting departures from the spirit and scope of the invention are intended to be included.

We claim:

1. An electromagnetic relay comprising a first and second planar flat yoke each yoke being of quadrilateral construction with four legs facing each other in pairs across a central opening of the respective yoke;

means for mounting the first and second yoke in superimposing and spaced apart relation, whereby each leg of one of the yokes is in registry with a leg of the other yoke in the direction of superimposing;

a coil, a coil carrier and an armature mounted between the yokes and extending in the central openings, the two yokes as mounted in spaced apart relation establishing a frame, the coil, coil carrier and armature being inside of that frame, the armature being mounted for pivoting on an axis;

magnet means including at least one permanent magnet and disposed for magnetic coupling the two yokes and functioning as spacers between the two yokes; and

contact springs with contact pieces extending from the means for mounting for cooperation with contacts on the armature.

2. A relay as in claim 1, the means for mounting including magnetically and electrically non-conductive elements in the four corners of the superimposed yokes and connected to the yokes for interconnecting them, the said contact springs extending from said elements.

3. A relay as in claim 2, wherein respective two superimposed legs of the yokes respectively define two spaces, into which the two ends of the rocking armature extend, the ends of. the armature carrying contact carriers for cooperation with the spring contacts, the spring contacts and contact carriers extending in the space between respective two aligned legs not interconnected magnetically be said magnet means.

4. A relay as in claim 3, the carrier having at least one magnetic means to provide a magnetic field'parallel to the surfaces of the contacts on the carrier.

5. A relay as in claim 3, wherein two spring contacts extend from a corner, cooperating respectively with two contact surfaces on opposite sides of the carrier.

6. A relay as in claim 3, the corner elements provided with stops for inhibiting deflection of the contact springs in direction opposite to the deflection as resulting upon contact making.

7. A relay as in claim 2, wherein the two yokes and the corner elements are held together by fastening means in each of the four corners.

I 8. A relay as in claim 2, wherein the yokes and comer elements are provided with recesses and projections for mutual engagement so as to impede relative turning.

9. A relay as in claim 2, wherein recesses are provided in the corner elements to receive portions of the contact springs serving as leads to run electric connections out of the frame.

10. A relay as in claim 9, wherein each corner element has at least one flange extending over one of the yokes, and in a recess thereof.

11. A relay as in claim 2, wherein two springs extend in spaced apart relation from a corner piece, the springs carrying contact pieces facing each other, a movable contact on the armature being disposed between thesecontact pieces for engaging either of them, each spring being flat with a narrower rear end lead, the springs being of similar contour so that upon mounting in the corner element, the rear end leads are laterally displaced from each other.

12. Relay as in claim 11, wherein the armature has twolaterally oppositely extending contact carriers at one end of an arm, the carriers extending towards two corner elements and respectively in-between the contact springs as extending from the corner elements, each contact carrier having two oppositely facing contact surfaces.

13. Relay as in claim 12, the contact carriers being relatively inflexible as compared with the contact springs, and being made of insulative material.

14. A relay as in claim 1, and including a frame around at least parts of the interconnected yokes along sides thereof, the relay including means for providing leads to the frame.

I 15. Relay as in claim 1, the coil carrier having projections reaching into the space between two legs of the yokes as aligned in direction of superimpositioni'ng.

16. Relay as in claim 1, and including a frame around the quadrilateral peripheries of the assembled yokes.

l7. Relay as in claim 16, the frame serving as plug element, with plugs extending in direction of superimpos-.

ing.

18. Relay as in claim 16, the frame having lateral slots for receiving lead laterally extending from the corner elements of the assembled yokes.

19. Relay as in claim 16, the openings being covered by foils.

20. A relay as in claim 1, the contact springs and the armature being mounted in such a manner between the yokes, and the coil carrier and the relay coil being only of such a depth, that the external dimensions of the yokes are equal to the external dimensions of the relay.

21. A relay as in claim 1, wherein the means for mounting the yokes and the contact springs interengage by means of recesses.

22. A relay as in claim 1, wherein at least two of the contact springs mounted in the region of the corners of the yokes and having their contact surfaces facing one another, have coincident contours, a narrow extension being provided colinear with or at right-angles to one of the long edges of each contact spring and at the end opposite the contact surface, by means of which electrical contact with the springs is established.

23. A relay as in claim 1, wherein flat contact actuating members and carriers of insulating material are provided laterally on the ends of the pivotal armature, said actuating members extending into the region of the flat contact springs and forcing an air flow along the contacts upon armature actuation and displacement of the carriers towards either of the contact springs.

24. A relay as in claim 23, wherein one or more permanent magnets are provided on the contact actuating members present, which generate a flux component parallel to the contact surface and normal to the actuating device.

25. A relay as in claim 1, wherein an air space between contact springs and yokes is occupied by a resilient energy-dissipating foam material.

26. A relay as in claim 1, wherein the pivotal annature is inserted within the coil carrier without any fixed bearing for its rotational axle.

27. A relay as in claim 1, wherein the means for mounting includes spacer pieces of insulating material, the spacer pieces and the contact springs being mounted at the corners of the yokes and being held together by fastening means.

28. A relay as in claim 27, the spacer pieces being situated respectively between two contact springs and being of such design that they include stops for the contact springs adjacent their contacts.

29. A relay as in claim 28, wherein at least one of the spacer pieces at each corner being fastened to a onepiece of composite casing enclosing the sides of the yokes.

'30. A relay as in claim 29, wherein the casing is provided with vertical grooves in the bottom surfaces alternating in depth in relation to one another, and in which the electrical connections are provided.

31. A relay as in claim 1, wherein a plug connection is provided in the form of a frame open at top and bottom and having a depth not exceeding the depth of the yokes as assemblied, the inside of the frame being provided with springs which are connected to soldering tages projecting downwardly from the frame of the plug, said springs being spaced so as to make connection with the external connections of the relay.

32. A relay as in claim 1, wherein the opening within the yokes, the side portions open to the exterior between the yokes, are covered by 

1. An electromagnetic relay comprising a first and second planar flat yoke, each yoke being of quadrilateral construction with four legs facing each other in pairs across a central opening of the respective yoke; means for mounting the first and second yoke in superimposing and spaced apart relation, whereby each leg of one of the yokes is in registry with a leg of the other yoke in the direction of superimposing; a coil, a coil carrier and an armature mounted between the yokes and extending in the central openings, the two yokes as mounted in spaced apart relation establishing a frame, the coil, coil carrier and armature being inside of that frame, the armature being mounted for pivoting on an axis; magnet means including at least one permanent magnet and disposed for magnetic coupling the two yokes and functioning as spacers between the two yokes; and contact springs with contact pieces extending from the means for mounting for cooperation with contacts on the armature.
 2. A relay as in claim 1, the means for mounting including magnetically and electrically non-conductive elements in the four corners of the superimposed yokes and connected to the yokes for interconnecting them, the said contact springs extending from said elements.
 3. A relay as in claim 2, wherein respective two superimposed legs of the yokes respectively define two spaces, into which the two ends of the rocking armature extend, the ends of the armature carrying contact carriers for cooperation with the spring contacts, the spring contacts and contact carriers extending in the space between respective two aligned legs not interconnected magnetically be said magnet means.
 4. A relay as in claim 3, the carrier having at least one magnetic means to provide a magnetic field parallel to the surfaces of the contacts on the carrier.
 5. A relay as in claim 3, wherein two spring contacts extend from a corner, cooperating respectively with two contact surfaces on opposite sides of the carrier.
 6. A relay as in claim 3, the corner elements provided with stops for inhibiting deflection of the contact springs in direction opposite to the deflection as resulting upon contact making.
 7. A relay as in claim 2, wherein the two yokes and the corner elements are held together by fastening means in each of the four corners.
 8. A relay as in claim 2, wherein the yokes and corner elements are provided with recesses and projections for mutual engagement so as to impede relative turning.
 9. A relay as in claim 2, wherein recesses are provided in the corner elements to receive portions of the contact springs serving as leads to run electric connections out of the frame.
 10. A relay as in claim 9, wherein each corner element has at least one flange extending over one of the yokes, and in a recess thereof.
 11. A relay as in claim 2, wherein two springs extend in spaced apart relation from a corner piece, the springs carrying contact pieces facing each other, a movable contact on the armature being disposed between these contact pieces for engaging either of them, each spring being flat with a narrower rear end lead, the springs being of similar contour so that upon mounting in the corner element, the rear end leads are laterally displaced from each other.
 12. Relay as in claim 11, wherein the armature has two laterally oppositely extending contact carriers at one end of an arm, the carriers extending towards two corner elements and respectively in-between the contact springs as extending from the corner elements, each contact carrier having two oppositely facing contact surfaces.
 13. Relay as in claim 12, the contact carriers being relatively inflexible as compared with the contact springs, and being made of insulative material.
 14. A relay as in claim 1, and including a frame around at least parts of the interconneCted yokes along sides thereof, the relay including means for providing leads to the frame.
 15. Relay as in claim 1, the coil carrier having projections reaching into the space between two legs of the yokes as aligned in direction of superimpositioning.
 16. Relay as in claim 1, and including a frame around the quadrilateral peripheries of the assembled yokes.
 17. Relay as in claim 16, the frame serving as plug element, with plugs extending in direction of superimposing.
 18. Relay as in claim 16, the frame having lateral slots for receiving lead laterally extending from the corner elements of the assembled yokes.
 19. Relay as in claim 16, the openings being covered by foils.
 20. A relay as in claim 1, the contact springs and the armature being mounted in such a manner between the yokes, and the coil carrier and the relay coil being only of such a depth, that the external dimensions of the yokes are equal to the external dimensions of the relay.
 21. A relay as in claim 1, wherein the means for mounting the yokes and the contact springs inter-engage by means of recesses.
 22. A relay as in claim 1, wherein at least two of the contact springs mounted in the region of the corners of the yokes and having their contact surfaces facing one another, have coincident contours, a narrow extension being provided colinear with or at right-angles to one of the long edges of each contact spring and at the end opposite the contact surface, by means of which electrical contact with the springs is established.
 23. A relay as in claim 1, wherein flat contact actuating members and carriers of insulating material are provided laterally on the ends of the pivotal armature, said actuating members extending into the region of the flat contact springs and forcing an air flow along the contacts upon armature actuation and displacement of the carriers towards either of the contact springs.
 24. A relay as in claim 23, wherein one or more permanent magnets are provided on the contact actuating members present, which generate a flux component parallel to the contact surface and normal to the actuating device.
 25. A relay as in claim 1, wherein an air space between contact springs and yokes is occupied by a resilient energy-dissipating foam material.
 26. A relay as in claim 1, wherein the pivotal armature is inserted within the coil carrier without any fixed bearing for its rotational axle.
 27. A relay as in claim 1, wherein the means for mounting includes spacer pieces of insulating material, the spacer pieces and the contact springs being mounted at the corners of the yokes and being held together by fastening means.
 28. A relay as in claim 27, the spacer pieces being situated respectively between two contact springs and being of such design that they include stops for the contact springs adjacent their contacts.
 29. A relay as in claim 28, wherein at least one of the spacer pieces at each corner being fastened to a one-piece of composite casing enclosing the sides of the yokes.
 30. A relay as in claim 29, wherein the casing is provided with vertical grooves in the bottom surfaces alternating in depth in relation to one another, and in which the electrical connections are provided.
 31. A relay as in claim 1, wherein a plug connection is provided in the form of a frame open at top and bottom and having a depth not exceeding the depth of the yokes as assemblied, the inside of the frame being provided with springs which are connected to soldering tages projecting downwardly from the frame of the plug, said springs being spaced so as to make connection with the external connections of the relay.
 32. A relay as in claim 1, wherein the opening within the yokes, the side portions open to the exterior between the yokes, are covered by foils. 